Two-way clutch



June 1945- w. v. THELANDER 2,379,024

' TWO-WAY CLUTCH Filed Dec. 12, 1941 2 Sheets-Sheet l 2,319,024 Two-war neuron it. Vincent Thelander, Auburn, Ind. Application December 12, 1941, Serial No. 422,614

24 Claims.

This invention relates to friction clutches and is more particularly concerned with a new and improved two-way clutch especially designed for use with a two-rate transmission in a tractor, tank, truck, or the like, but of course is suitable for other uses. 1

The principal object of my invention is to provide a friction clutch of the kind mentioned, in which a single pressure plate is arranged to cooperate selectively with either of two clutch disks, the one driving a shaft associated with one gear train and the other driving a quill surrounding the shaft and associated with the other gear train, whereby when the one disk is engaged the other turns idly with its gear. train, and vice versa, the purpose being to enable quick change in the drive ratio by merely shifting the clutch instead of having to shift gears in the transmission.

An important feature of the present invention consists in the provision of a single spring means outside the clutch proper and hence isolated from the parts subject to heating in the operation of the clutch, the said single spring means cooperating with clutchactuating levers so as to apply spring pressure to the pressure plate in. either direction, said spring means af-' fording substantially constant pressure on the pressure plate in either position of clutch engagement and permitting movement past dead center position of the toggle linkage operating the actuating levers, whereby the clutch is automatically maintained in either engaged position under spring pressure until moved manually to neutral position orto the other engagedp'esition.

Another object of my invention consists in the provision of spring pressed plungers on the pressure plate, some of which project forwardly for engagement withthe back face of the flywheel and others of which project rearwardly' for engagement with the back plate to maintain the pressure plate in a central position clear of both clutch disks when the throw-out collar is in neutral position.

The invention is illustrated in the accom- Denying drawings, in which- Figure l is a longitudinal section through a two-way clutch made in accordance with my invention, half of the complete section being omitted to conserve space and permitshowin the parts on a larger scale;

Figs. 2, 3, and 4 are fragmentary sectional details showing other portions of the clutch of Fig. i, Fig. '3 being a sectional detail on the line (ill. 192-48) 3-8 of Fig. 2, and Fig. 4-'being a sectional detail on the line d-t of Fig. 2; I

Fig. 5 is a section similar to Fig. 1, illustrating another clutch of modified or alternative construction, and

Fig. 6 is a diagrammatic illustration of the two-rate transmission in connection with which the clutches of my invention are employed.

Similar reference numerals are applied to corresponding parts throughout the views.

Referring first to Figs. 1 to 4, the reference numeral l8 designates the flywheel of an engine, and ii the back plate thereon. i2 is a driven shaft extending rearwardly from the flywheel adapted for direct connection with the propeller shaft or to .be extended into the front end of the gear box of a transmission, and i3 is a quill surrounding the shaft and serving as an auxiliary driven member, the shaft l2 being for high ratio drive and the quill It for low ratio drive, as will soon appear. The'shaft if has the usual pilot bearing l5 supporting the front end thereof at the center of the flywheel Ill. I5 and ld-are clutch disks, the disk I5 having its center hub l1 splined on the front end of the shaft if to transmit drive from the flywheel to the shaft when the disk I5 is engaged, and the disk is having its hub l8 splined on the front end of the quill iii to transmit drive from the flywheel to the quill when the disk I6 is engaged. At H are shown the usual pads or facings on the clutch disks, and at 20 is indicated a pressure plate between the two disks, adapted when moved forwardly to engage disk IS with the driving face 2! on the back of the flywheel and the companion driving face 22 on the front of the pressure plate. The pressure plate is also movable rearwardly for engagement with disk it to cause engagement thereof with the driving face 23 on the back plate H and the companion driving face 2 3 on the back of the pressure plate. The latter is suitably cast like the flywheel and back plateand the faces Til-26 are accurately machined onthese cast parts to cause smooth clutch engagement. The back plate is suitably bolted to the flywheel by means of its marginal flange portion 25 and has a plurality of drive lugs 26 cast integral therewith and projecting forwardly therefrom in circumferentially spaced relation for slidable driving engagement in radial notches 27 in the periphery of the pressure plate 20. Hardened wear plates 28 are riveted onto opposite sides of the lugs 28, asshown, to minimize wear. The pressure plate has a plurality tions. 3| for slldably mounting stamped sheet 5 metal rings 32 and 33, through which the reduced end portions 3| of the .posts project, as

shown. The reduced 'endportions 3| of the posts also serve as supports for coiled compression springs 33 which surround these end portions 3| and have engagement at their opposite ends with the rings 32 and 33. Additional coiled compression springs 33 are interposed between the rings and supported at their opposite ends by hollow cylindrical'bosses 33 and from the rings. The springs 34 and 33 are all preloaded when nuts 33 threaded on the further reduced ends of the posts are tightened against the shoulders 33. The rings 32 and 33 have annular flanges and 4| on their inner peripheries in concentric relation to the rings and back plate and pressure plate, and these flanges are in axially spaced relation so that clutch actuating levers 32 and 33 for selective. engagement of'the clutch in either of the two operative positions of the pressure plate can further compress the springs to have the clutch engaged under increased spring pressure in either of the two aforesaid positions of the pressure plate. \The levers 32 and 33, of which there will 30 preferably be six sets in equally circumferentially spaced relation with respect to the back plate, are mounted in paired relation, as shown in Fig.

i 2, between lugs 33 on common pivot pins 33,

each of the levers 42 being bifurcated, as in- 35 lation under those conditions to the front face dicated, to provide two bearings 33 to receive therebetween the single bearing 31 of theassociated lever 33. Fingers 33 on the levers project radially outwardly and have rounded outer end 31 struck inwardly l5 namely,

with the pivots 3! normal to the axis of rotation,

clutch disk under a. pressure substantially above The present clutch is of the preload pressure. the over-center" type and provision is accordingly made for movement of the throw-out collar 33 past the dead center positions, both in forward movement from the neutral position and in rearward movement from the neutral position. Thus, for example, in the forward movement of the collar 33 there is maximum compression or the springs when the pivots 33 arein dead center relationship to the pivots II, when said pivots are in the same plane and at that point the lug 33 on the collar 33 is in closely spaced relation to the back face 31 on the 'back plate and is arranged to be brought 20into engagement with said face by the slight amount of additional forward movement of the collar 33 necessary, the toggle links 33 in that slight additional movement being moved "over center. There is, therefore, no appreciable re- 25 duction in spring pressure in the movement pastcenter, but the spring pressureis made effective to hold the-throw-out collar resiliently in theextreme forward positiomso that the clutch is not apt to be accidentally disengaged. Generally speaking, the same operation occurs in the rearward movement of the collar 33, the springs having maximum compression when the pivots 53 are in dead center relationship to the pivots i2, and the lug 33 being in closely spaced re- 33 of a ring 33 carried on the back plate. Slight further rearward movement of the collar 33 under those conditions brings the lug 33 into engagement with the ring 33 and the toggle links portions for sliding engagement with the flanges 40 "and is thereby moved "over center." Here 33 and (as clearly appears in Fig. 1. Toggle links 48 and 33 are pivotally connected to the ends of the levers 32 and 33 remote from the pivot pin 43, as at II and 32, and these links are pivotally connected, as at 133 and 33, to a manually reciprocable throw-out collar 33. There are, 'of course, as many sets of toggle links 38 and III as there are levers 32 and 33. The pivots 33 and 33 are much closer together than the pivots II and 32 so that when the collar 33 is moved for- 50 wardly from the neutral position shown the links 33 move the levers, 32 in a clockwise direction toward operative position as the pivots 33 move, toward a plane through the pivots 3| normal to the axis of rotation, the levers 43 meanwhile being retracted from operative relationship to the flange 3| by the links 33.- On the other hand in the rearward movement of the collar 33 from the neutral position shown, the links 33 move the levers 33 in a counterclockwise direction toto ward operative position as the pivots 33 move toward a plane through the pivots 32 normal to the axis of rotation, the levers 42 meanwhile being retracted from operative position to the flange 43 by the links 33. In the initial move- 05 ment of the levers 32 toward operative position, 5 the pressure plate 23 is brou ht into engagement with the clutch disk l3, and in the further move-' ment the ring 32 is moved toward the ring 33 to compress the springs 33 and 33, thereby engaging the clutch disk l3 under a presisure Sub-. stantially above the preload pressure of the springs. In the initial movement of the levers 33 toward operative position, the pressure plate 23 engages the clutch disk It, and thereafter in 73 again it is clear that there is very little reduction in spring pressure as a. result of the movement over center and the spring pressure is made eflective to hold the collar 33 resiliently in the extreme engaged position to avoid accidental disengagement of the clutch. The ring 53 is fastened to the lugs 33 by means of screws 63 and, as indicated at 3|, is cut away on the inner periphery to provide the required operatportion of the pressure plate 23.are effective to hold the collar yieldingly in that position so as to prevent accidental engagement of the clutch, the plungers 32 serving yieldingly to prevent rearward movement of the pressure-plate by light frictional contact with the inner face 23 of the back plate, and the plungers 33 servinglikewiseito prevent forward movement of the pressure plate by light frictional contact with the back face 2| of the flywheel. There are preferably three plungers 32 in equally circum- .ferentially spaced relation relative to the pressureplate 23 and three plungers 33 in equally circumferentially spaced relation relative to the pressure plate 23. These plungers are preferably disposed in pairs on opposite sides of the notches 21 in the pressure plate, as illustrated in Fig. 2, there being preferably three drive lugs 23 on :the back plate to cooperate with three equally circumferentially. spaced notches 21 =in the periphery of thepressure'plate. Each of the stem portion 65 reciprocable freely in a hole 66 communicating with the bore. A light coiled compression spring 61 surrounds the stem 65 in the bore 65 and acts to hold the plunger normally in the extended position. A washer 68 riveted on the outer end of the stem 65 limits the outward movement of the plunger.

In operation,-the clutch, as previously indicated, is .used in conjunction-with a two-rate transmission where the shaft 12, as shown in Fig. 6, extends rearwardly from the clutch and has the rear end portion 69 either directly connected through a universal joint with the propeller shaft of the tractor, truck, tank, or other vehicle or extended into the front end of the gear box of I a change speed transmisson providing any desired number of speeds for forward and reverse drive. The quill it which provides the low rate drive has a gear ill on the rear end thereof meshing with the larger gear H of a two-gear cluster, the smaller-gear 12 of which meshes with a large gear 73 on' the shaft 92, whereby "to drive the shaft it at a reduced speed when the disk it. on the quill i3 is engaged. The cluster 'H'|2 is supported on a spindle M suitably mounted in spaced parallel relation to the shaft l2 and quill E3. of course, when the disk IS on the shaft I2 is engaged, the quill l3 and disk l6 are driven idly by reason of the reduction gearing connection with the shaft l2. Forward movement of the throw-out collar 55 by means of a manually operable clutch pedal or lever (not shown) causes engagement of'the disk it in the manner previously described. When the throw-out collar 55 is moved rearwardly by means of a manually operable clutch pedal or lever, the disk I5 is engaged in the manner previously described. The springs 36 and 35 in addition to providing resilient engagement so that close adjustment is, not required even though the clutch is of the over-center type provide substantially constant pressure and accordingly non-slipping engagement regardless of the usual wear on the clutch facings l9. In addition the springs, as previously described, act to hold the throw-out collar 55 resiliently in either extreme position to avoid likelihood of accidental disengagement of the clutch. n the other hand when the throw-out collar 55 is in the neutral position shown in Fig. 1, the plungers 52 and 83 hold the pressure plate 20 yieldingly in the mid-position out of engagement with both disks l and so that the likelihood of accidental engagement of the clutch is avoided.

The clutch shown in Fig. 5 is similar to that disclosed in Figs. 1' to 4 and is also intended to be used with a two-rate transmission like that shown in Fig. 6. In this clutch the parts that correspond to parts in the other clutch have been numbered correspondingly, using prime numbers. The posts It rigid with and projecting rearwardly from the pressure plate have flat faces 15 on the opposite sldes thereof and have a close work ng m flywheel and back plate constituting the driven: A

7 elements, a pressure plate between saiddisks I 8|, a predetermined plfeload pressure is established. Hardened steel stirrups 92 and B3 are set in the cast rings 32' and iltflrespectively, for cooperation with actuating forks 86 pivoted, as at 85, between lugs -85 cast integral with and projecting rearwardly from the back plate H. The fingers 58 on each-fork are engaged in the associated stirrups 82 and 83 so that when the fork M'is oscillated in one direction or the other, the pressure plate 20 is moved correspondingly and the springs 36' and such other springs as may be provided between the rings 32' and 38', like the springs in Fig. 1, are compressed beyond the preload pressure after the pressure plate has engaged the clutch disk W or it, as the case may be. The fork 86 is arranged to be oscillated in eitherdirection from the central neutral position shown by reciprocation of the throw-out collar through the lost motion link connections shown, links so and 87 being pivotally connected at one end on a common pivot pin 88 to the throw-out collar and having pin and slot connections at their other ends with the fork M, as indicated atfiQ and on. The pressure plate 20', it will be understood, is equipped with spring pressed plungers like those shown in the other clutch, so as to hold the pressure plate yieldi'ngly in the middle neutral position and avoid likelihood of accidental engagement of the clutch. The forward end 9| of the throw-out collar is arranged to engage the back face 92 of the back plate when the throw-out collar is moved to an extreme forward position wherethe pivots" are moved slightly past dead center relationship to the pivots 89, similarlyas in the over-center movement described in the other clutch. Similar provision may be made for limiting movement of the throw-out collar past the dead center position in its rearward movement as described in the other clutch. In that way the clutchis held engaged resiliently and there is avoided likelihood of accidental disengagement, and, of course, the springs 34' and such other springs as may be provided between the rings 32' and 33' afford substantially constant engagin pressure 150 pensate for wear in the operation of the clutch, similarly as in the other clutch. The operation of this clutch is so closely similar to the operation of the other clutch no further description is considered necessary.

It is believed the foregoing description conveys a good understanding of the objects and advantages of my invention- The appended claims have been drawn to cover all legitimate modifies" a back plate in fixed axially spaced relation-to n the flywheel and turningtherewith, of two separate and independent clutch disks between the turning with the flywheel and back plate' movable in either direction fronts neutral position for driving engagementiv ith either of said ably six in equally circumferentially spaced rela tion relative to the back plate, have reduced cyl ndrical end portions "(which are further reduced at their extremities l9 and threaded to receive nuts 80 to hold the cast rings 32' and 33' in'place on the posts with coiled compression springs 34' compressed therebetween, similarly as in the other clutch. When the washers under disks, means drivenby each of .said clutch disks. and means for moving the pressure plate to either clutch engaging position, comprising a resilient element and an over-center clutch'actuating lever 7 means, the resilient element being carried bythei pressure plate and flexible in either. direction for! x resilient engagement of said pressure-"plate' withi"" j I either of said disks, and said over-center clutch l I the nuts 80 are tightened against the shoulders actuating lever means belngpivoted on the back ments, one arran plate for movement relative to said resilient ment to move the pressure plate to driving position, said resilient element cooperating with said lever means so as to be flexed in one directionin the engagement of the pressure plate with one of said disks and flexed in the opposite direction in the engagement of the pressure plate with the other of said disks, whereby to hold either ofsaid disks resiliently engaged.

2. In a friction clutch, the combination with a flywheel constituting the driving element and a back plate in fixed axially spaced relation to the flywheel and turning therewith, of two. separate and independent clutch disks-between the flywheel and back plateconstituting the driven elements, a pressure plate between 'said disks turning with the flywheel and back plate and movable in either direction from a neutral posi- 'tion for driving engagement with either of said disks, means driven by eachof said clutch disks,-

- ring means in concentric relation to said plates eledisk and compress said compressible resilient means so as to engage the clutch resiliently.

5. In a friction clutch, the combination with a flywheel constituting the driving element and a back plate in fixed axially spaced relation to the flywheel and turning therewith, of two separate I and independent clutch disks between the flywheel and. back plate constituting the driven elements, a pressure plate between said disks turnconnected to turn with the pressure'plate and guided on said connection for limited axial movement with respect to the pressure plate and adapted to support springs in caged relation thereto in preloaded condition, a plurality of springs caged in circumferentially spaced relation to said ring means in a compressed condition,

and positive acting over-center means operatively associated with said ring means and movable relative to the back plate to move the pressure plate through the medium of said ring meansand springs in either back plate and further compress said springs so as to engage the clutch resiliently under increased spring pressure.

3. In a friction clutch, the combination of a flywheel constituting the driving element, 'a back plate for the flywheel, two separate and inde-" pendent clutch disks constituting the driven eleged to engage the flywheel and the other arranged to engag the back plate,-a pressure plate turning with the back plate and disposed between said disks to engage either disk selectively, means driven by each of said clutch disks, a plurality of springs carried on the pressure plate in circumferentially spaced relation, positive acting clutch actuating means for moving the pressure plate in either direction to en'- gage the clutch, and a single intermediate means for transmitting pressure from the clutch actuating means to the springs in either direction and thence to the pressure plate, whereby to' engage the clutch resiliently in either direction.

4. In arfriction clutch, the combination with direction relative to .the

tive'acting lever means mounted for pivotal a flywheel constituting the driving element and a back plate in fixed axially spaced relation to the flywheel and turning therewith, of two separate and independent clutch disks between the flywheel and back plate constituting the drivenelements, a pressure-plate-beii;v\een said, disks turning with the flywheel and backifiatemnd plate, whereby to 1.18886 either clutch.

ing-with the flywheel and back plate and mov-.

able in either direction from a neutral position for driving engagement with either of said disks, supporting means carried by the pressure plate and adapted to support ring-members behind the back plate, means driven by each of said clutch disks; a pair of ring members in concentric relation to said plates'and guided on said supporting means for a limited axial movement with respect to the pressure plate and adapted to support springs, a plurality of springs supported in circumferentially spaced relation to said rings..

and lever means mounted for pivotal movement relative to the back plate and operatively enga ing the rings to move the pressure plate in either direction relative to the back plate to engage either clutch disk and load the aforesaid springs so as to enga e the clutch resiliently.

- B. In a friction clutch; the combination of a flywheel constituting the driving element, a back plate for the flywheel, two separate and independent clutch disks-constituting the driven elemen s the other arranged to engage the back plate, a pressure plate turning with the back plate and disposed between said disksto engage either disk selectively, means driven by each 01' said clutch disks; a plurality otsprings carried on the pressure plate in circumferentially spaced relation, a pair of rings carried on the pressur plate and guided for a limited axial. movement with respect' thereto and normally supporting said springs compressed in preloaded condition, posimovement relative to the back plate and operatively'engaglns said ringsto move the pressure plate in either direction relative to the back plate to engage either of said clutch disks and further compress the aforesaid springs so a to engage the clutch resiliently under increased spring pressure, a throw-out member guided for movement toward and away from the back plate,

and lever actuating means carried on said throwout member and arranged upon movement thereof one way or the other from a neutral position to move said lever means to one or the otherof two extreme positions inwhich the clutch is engaged resiliently and locked in such condltionso 4 long as said throw-out to neutral position.

7.'In a friction clutch, the combination oi a flywheel constituting the driving element, a back member is not returned plate for the flywheel, two separate and independent clutch disks constitgti'ng th e' driven elements, one arrangedt'ifehgagethe flywheel and the other arranged to engage the back plate. a

pliessllre plateturning with thefback plate and disposed-between said disks to engage either disk selectivelyimeans driven by each of said clutch disks, a pluralltiof springs carried .on the pressure plate in circumferentially spaced relation. a

pair of rings carried on the pressure plate and guided for a limited axial movement withrespectthereto and normally] supporting said' springs compressedin preloaded condition. posi-, tive acting lever means mounted for pivotal one arranged to engage the flywheel and movement relative to the back plate and operatlvely engaging said rings to move the pressure plate in either direction relativeto the back plate to engage either of said clutch disks and further compress the aforesaid springs so, as to engage the clutch resiliently under increased spring pressure, a throw-out member guided for movement toward and away from the back plate, and means providing a lost motion operating connection b tween said throw-out member and said lever means.

8. In a friction clutch, the combination of a flywheel constituting the driving element, a back plate for the flywheel, two separate and independent clutch disks constituting the driven ele ments, one arranged to engage the flywheel and the other arranged to engage the back plate, a pressure plate turning with the back plate and disposed between said disks to engage either disk selectively, means driven by each of said clutch disks, a plurality of springs carried on the pressure plate in circumferentially spaced relation,

positive acting lever means for moving the pressure plate in either direction to engage the clutch,

a single intermediate ring means for transmit ting pressure from the lever means to the springs f in either direction, whereby to engage the clutch resiliently in either direction, and spring means on the pressure plate subject to deflection when the clutch is engaged and tending otherwise normally to hold the pressure plate yieldingly in a neutral position between the clutch disks.

9. A friction clutch as set forth in claim 6, including spring means on the pressure plate subject to deflection when the clutch is engaged and tending otherwise normally to hold the pres.- sure plate yieldingly in a, neutral position between the clutch disks when the throw-out member is in neutral position.

10. A clutch as set forth in claim 1, including resilient means on the pressure plate subject to deflection when the clutch is engaged and tend ing otherwise to hold the pressure plate normally in a neutral position out of engagement with both clutch disks.

11. In a clutch mechanism, the combination of clutch disks connected to separate rotary parts, a pressure plate shiftable to driving en gagement selectively with either clutch disk, ring means in concentric relation to said plate connected to turn therewith and guided on said connection for limited axial movement with respect thereto and adapted to support springs in caged,

relation thereto in preloaded condition, .a single set of springs caged in ,circumf erentially spaced relation to said'ring means in a compressed condition and adapted to apply the spring pressure, thereof alike to either disk, and positive acting means cooperating with said ring means to move the pressure plate in either direction to engage either clutch disk resilie'ntly under the spring.

pressure urine single set of springs and further compress said springs, whereby the cluteh disk is engaged resiliently under increased pressure that is'substantially alike in the engage merit of either disk. e

12. In a. clutch mechanismthe combination of clutchdisks connected to separate rotary parts,

a pressure plateshiftable to driving engagement selectively with either clutch disk, a single set,

of springs carried on the'pressure plateincirv cumferentially spaced relation and adapted to apply the spring pressurethereoi allketo either disk, positive acting means for moving the pres- 78 Dressurejlate to sure plate in either direction to engage either the combination to separate rotary 1o a pressure plate shiftable to driving engagement selectively with either clutch dish, a single spring means carried on the pressure plate and adapted to apply the spring pressure thereof alike to either disk, and positive acting means operatively connected with .the pressure plate through the medium of said spring means so as i to transmit pressure therethroughto the pressure plate in either direction, whereby to engage the clutch resiliently in either direction and under substantially the same spring pressure.

14. In a clutch mechanism, the combination of clutch disks connected to separate rotary parts, a; pressure plate shi'ftable to driving engagement selectively with eitherclutch disk, an-

nular spring caging means connected for rotation with the pressure plate inconcentrlc relation therewith, a single set of springs caged in circumferentially'spaced relation. to said annular caging means in compressed condition to a preload pressure, and positive acting means having operative engagement with the annular caging means toactuate said pressure plate for resilient engagement of either disk under increased spring pressure that is substantially alike in the engagement of either disk, said positive acting means being arranged to compress said springs above the preload pressure after engagement of the pressure plate with either disk.

15. In a clutch mechanism, the combination 40 oi clutch disks connected to separate rotary parts, a pressure plate shlftable to driving engagement selectively with either clutch disk, an- I to engagement of either disk under spring pressure that is substantially alike in the engagement oi either disk, said positive acting means being ar-' ranged to compress said springs after 8 8 of the pressure plate with either disk. 16. In a friction clutch,.th'e combinationwith a flywheel constituting the driv ng element and a back platein fixed axially spaced relation to the flywheel and turning therewith, or two separate and indepment clutch disks 50 wheel and men-ts, a pressure plate betweensaid disks tuniing with the flywheelandback-plate and. movable .ineithe -mdipection from a neutral position spring w im-"driving engagement with either ots'aid'disks. as means driven by each or said clutch disks, and means or moving the, pressure plate to e'ltherf comprising a. resilient, lever means, said resilient ehement being carried bycthe pressure) Plate and flexiblein either direction for resilient. T engagement or the pressllne plate with either of,

clutch engaging position, element fand clutch actuating said disks, and said clutch actuating levenmeans being pivoted on the back plate for movement driving position, said resilient between .l eflr- I kplate constituting the driven elerelative to said resilient element to move the a in compressed condition on said rings, and positive acting clutch actuating means operatively plate through the medium of said ring mean and disk, and a single spring means in circumferenm'eans so as to be stressedsubstantially alike with eitherdi'sk, and positive acting mechanical means for moving said ring assembly selectively in either direction for driving engagementoi' the clutch disks connected to separate rotary pa ts, a

gselectively with either clutch disk, is single spring with either disk carried on the pressure plate in pendent clutch disks constituting the driven eleants, one arranged to engagethe flywheel and Y disposed between said disks her reciprocable toward and element cooperating. with said lever means so as to the pressure plate in either direction and lock to be'flexed in one direction in the engagement the clutch selectively in either engaged position. 0! the pressure plate with one of said disks and 21. In a friction clutch, the combination with flexed in the opposite direction in the engagea flywheel constituting the driving element and meat 01' the pressure plate with the other of 5 aback plateinflxedaxiallyspaced relationtothe said disks, whereby to hold either or said disks flywheel-and turning therewith, of two separate resiliently engaged. and independent clutch disks between the fly- 17. In a friction clutch, the combination with wheel and back plate constituting the driven elea flywheel constituting the driving element and ments, a ressure plate between said disks turnaback plate in flxed axially spaced relation to ing with the flywheel and back plate and movable the flywheel and turning therewith, 01! two sepain either direction from a neutral position for rate and independent clutch disks between the driving engagement with either of said disks, flywheel and back plate constituting the driven means driven by each of said clutch disks, a pair elements, a pressure plate between said disks of ring members in concentric relation to said turning with the flywheel and back plate and plates and guided tor a limited axial movement movable in either direction from a neutral posiwith respect to the pressure plate and adapted to tion for driving engagement with either of said holdand compress a compressible resilient means disks, means driven by each of said clutch disks, thereon, a compressible resilient means caged on ring means mounted on the pressure plate in consaid ring members, a throw-out member recipcen-trlc relation thereto, to turn therewith and rocable toward and away from the back plate, guided on said mountingfor limited axial moveand over-center lever means operatively connectment'with respect to the pressure plate, a pluing said throw-out member and said ring memralityoi coiled compression springs supported bers' so as to permit engagement of the clutch I resiliently in either direction and lock the clutch 5 in either engaged position. 2.2. In a friction clutch, the combination with flywheel constituting the driving element and a associatedwith said ring means and movable relative to the back plate to move the pressure springs -to either clutch engaging position and to i'urther compress the aforesaid springs so that the clutch is engaged resiliently under increased spring pressure.

i8. In a clutch mechanism, the combination oi'two clutch disks connected to separate rotary parts, 'a ringassembly including pressure plate means disposed between the disks and shiitable to irictional engagement selectively with either flywheel and turning therewith, of two separate and independent clutch disks between the flywheel and back plate constituting the driven elements, 9. pressure plate between said disks turning with the flywheel and back plate and movable in either direction from a neutral positionior; driving engagement with either oi said disks,

means driven by each of said clutch disks, supportingmeans carried by the pressure plate and adapted to support ring members behind the back 1 plate, a pair 015- ring members in concentric rela- 40 tlon to said plates and guided on said supporting means for a limited axial movem'entwith respect to the pressure plate and adapted to support springs, a plurality oi springs supported-in circumierentiially. spaced relation to and rings, a throw-out member reciprocable toward and away from the back plate, and over-center lever means I operatively connecting said throw-out member and .said ring members so as to permit engagement of the clutch resiliently in either direction and lock the clutch in either engaged position.

23. In a friction clutch, the combination of a flywheel constituting the driving element, a back flail! spaced relation in the 4 ring assembly and op'eratively associated with pressure plateupon engagement or the pressure plate 'means pressure-plate means with either clutch .disk.

-' 19. In a clutch mechanism, the combination of pressure plate sh'iitabie 'to driving engagement means tor-resilient engagement of the clutch circumierentially spaced relation, and positive mechanical means cooperating with the spring means to transmit pressure resiliently through'sa'id spring means to the pressure plate pendent clutch disks constituting the driven elements, one arranged to engage the flywheel and her arranged to engage the back plate, a

plate for the flywheel, two separate and inde backplate in fixed axially spaced relation to the 1 in either direction, whereby to engage the clutch pressure p ate tumipg with the back plate and resiliently in either direction withsubstantially disposed between said3isks toengauitlierldisk the samesprlng pressure.

. 80. In a iriction clutch, the cabinatiomoi' a iiywheelconstituting the-drivin element, a, back plate for the flywheel, two separate and indedisks, a plurality oi springs carried on the pres- 7 sure plate in circumi'erentially spaced relation,

' a pair of rings carriedon the pressure plate and guided for a limited axiaimofiment with respect thereto and normally supporting said springs compressed in preloaded condition, a the"back platewow-out member-guided ionm vement toward 4 4 to engage either disk d awa irom the back plate, and ov nter selectively, means driven byeach of said clutch lever meanrp ding a lost motion oper connection between dthrow-out member and said rings to permit resilient engagement oi the clutch in either direction in which the springs are further compressed for engagement of the plate. and over-center lever means operatively clutch under increased spring pressure, and also connecting said throw-out member and said cage permit locking oi the clutch in'either engaged m "Mt P sure through said springs 1 position, a l

other arrangcd to engage the back plate, a pressure plate turning with I in circunii'erentially spaced relation, to W ns for said springs. a throw-out memaway from the back selectively, means driven by each of said clutch 24. A friction clutch, comprising two separate and independent clutch disks constituting the driven elements, a pressure plate turning with a flywheel and disposed between said disks and movable axially from a neutral position in either direction for driving engagement with either disk, a. spring means supported on one side of the pressure plate in preloaded conditionand caged on the supports, and positive acting mechanical clutch actuating meansior moving said supports and the pressure plate through said preloaded spring means in either direction to engage either clutch disk with substantially the same engagin pressure by compression of the same springmeans above the preload pressure to the same extent in either such engagement. 

